The home secretary's decision to move scores of paedophiles out of hostels next to schools backfired spectacularly last night amid concerns many were now under less stringent supervision than before John Reid's unprecedented intervention.

A Home Office source told The Observer that many of the 70 sex offenders moved out of 11 hostels near to schools and nurseries were now being housed either in voluntary hostels run by church groups or in bed and breakfast accommodation. 'There's little option because of a shortage of specialist accommodation units,' the source said.

Probation experts warned that in both types of accommodation the level of supervision of sex offenders is not as high as that in specialist hostels.

A report earlier this year was critical of the fact that Anthony Rice, the sex offender who killed Naomi Bryant, was placed in a voluntary hostel where his movements often went unobserved, despite being judged a risk to the public.

Bed and breakfast accommodation is not considered suitable for potentially dangerous offenders because it is difficult to monitor their movements - unless a probation officer or social worker is also a resident at the location.

'The great anxiety is that people may well have been moved into situations that are less safe,' said Martin Wargent chief executive of the Probation Boards Association which represents those who sit on the 42 probation boards across England and Wales. 'Really there should have been professional judgment about the risks these people posed before decisions to move them were taken.'

New guidelines governing the removal of sex offenders issued by the Probation Service and obtained by The Observer acknowledge that moving the men may increase the risk they pose to the public. 'If there is concern that moving an offender will reduce the level of protection afforded to the public, this should be minuted together with an appropriate explanation,' the guidelines states.

More offenders are likely to end up in temporary unsupervised accommodation unless new hostel accommodation is built. A strategy document issued by the Home Office earlier this year identifies a need for 'more secure and suitable accommodation'. The document, obtained by this newspaper, identifies accommodation shortfalls across the country.

In the east of England, for example, there is capacity for 149 dangerous offenders but a projected need of enough accommodation to house up to 188 people. In London there is currently capacity for 272 male offenders but a projected need for 370 places.

The Home Secretary took the decision to move the offenders following pressure from the News of the World newspaper, which mounted a campaign to identify hostels which house sex offenders close to schools. Following the decision Reid was accused of giving in to 'lynch mob law' by many probation experts.

Reid also pledged to re-examine the merits of introducing a US-style 'Megan's law', which would give parents greater information on paedophiles living in their area, and promised to send the Home Office minister, Gerry Sutcliffe, to visit the US on a fact-finding mission.

But the decision has been attacked by child protection experts. 'We have to explore ways of making communities safer,' said Donald Findlater, deputy director of the Lucy Faithfull Foundation, a child protection campaign group. 'But I would be very concerned if we all thought Megan's law was the answer. The police and probation agencies do a remarkably good job of managing risk. It's never going to be perfect.

Roger Hill, director of the National Probation Service, defended the decision to move the offenders to new accommodation. 'All the accommodation we use has been fully risk assessed and all those offenders that have been moved were subject to a rigorous and comprehensive risk assessment prior to relocation,' Hill said. 'The majority have been accommodated in alternative approved premises.'